herbko

Fred. Thanks for taking the time to share your experience. I agree with James. That post is an interesting article in itself. I've been using a Canon 100mm + 1.4x teleconverter and a Canon 500D (+2 diopter) in combinations for most of my shots so far. I think I'll get a set of extensions and try them out in the future. It's true that there are optical limits that will limit resolution at high magnification, but I don't think the above is a good example of how that works. Taken to the other extreme your example would imply that a lens focused at 5 meters would only have half the resolution of the same lens focused at 10 meters. I came across this extensive test chart for Canon lenses used with diopters and tubes by Bob Atkins at photo.net awhile ago. It's very handy. http://www.bobatkins.com/photography/eosfaq/closeup.htm

That's the same working distance for the 100mm lens by itself. So at least at that range it behaves like a 1.7x teleconverter. Thanks Paul.

That still gives a magnification of ~1.7x. Very good. Actual focal length at macro focus is complicated. In practice, it's really the working distance, front of the lens to subject, that's of most interest. While you're testing, please check the minimum magnification also i.e. what's the biggest subject that will focus. Thanks for checking this out.

Interesting! If it does deliver 2:1 on the 100mm then it's better than a 1.4x. Any sense of change in focal length? Try focusing to 1:1 with the 100mm with and without the convert and note the distances between lens and subject.

Thanks for the update. That's good news.

Nice shots Jenny. Beautiful colors. Any idea how the place has recovery from the tsunami?

The two of you can't even agree to disagree.

Perhaps I haven't seen enough good film sunballs shots to be much of a judge. If you think they are inferior to film shots, I really would like to know the details and perhaps have something to work on the next time out. Which cameras have you tried to shoot sunballs with? It seems to me to that before making a statement like "digital can't do sunballs" one should have tried a wide range of cameras and techniques.

As one who's never shot film, I can't give a proper comparison. However, I think the problem of shooting sunballs is over stated. I certainly don't avoid taking these shots. Here's a few samples from Wakatobi, my most recent trip.

Welcome home James. Have a great Safari.

I travel with the camera in the housing with 50mm lens and macro port all assembled. That way if the TSA ever want to examine it, the whole setup is a camera. I can take photos with it. So far no one has ever asked to look inside my carry on.

Has anyone tried this lens on a 5D or 1ds? It'd be interesting to see how much of the image beyond the cropped sensor edge is useful.

Very sad news indeed. We will all miss him.

Nice work Mike. Love the tunnel of Jacks with sunlight, #1412, but where's the manta. Bali is a great dive destination.

Is this an obscure Canadian custom?

Oops. Sorry. I blame it on this age thing. I do see that guy some of the times. In lots of cases, he's out at the line directing traffic, telling people which of the N lines to go to and not watching the input to the x-ray.

Things must be different in Texas. I can't remember ever having someone else load my stuff into the x-ray machine.

I'm not a fan of the TSA, but I wouldn't even consider this a TSA screw up. They have one staff member watching the metal detector and one watching the x-ray monitor. That should be enough to cover security. I don't think adding another one at the x-ray input to cover the one in a billion case that a baby gets put on justifies the cost.

This gets my vote. That's fantastic! Love the tiny diver in the background.

Between ISO 100 and 1600 changing the ISO setting will change the gain in the analog amplifiers between the sensors and the analog-to-digital converter. It's good to set the gain ( choose the ISO ) high enough to use the full range of the analog-to-digital converter but not so high that the highlights get clipped. 100 to 1600 is the full range for the 5D. Both ISO 50 and 3200 just adds a tag to the raw file and changes the exposure. It's useful if you're shooting JPEG.

Dynamic range and good high ISO performance are related. For sunball shots it's often necessary to way underexpose parts of an image to avoid overexposing the sun. The dark parts are brighten in post processing and is effectively shot at high ISO even though the camera setting is ISO 100.

16bit TIFF files are BIG. For example the raw files form my 5D are typically around 10 to 12MB the converted TIFF files are 75MB uncompressed and not that much smaller with LZW compression. That's a huge difference in disc space. I don't know this in great detail, but from what I've read, I think it is possible to preserve all essential information in converting to DNG. I think camera makers can adopt DNG without compromising image quality if they choose to. I'm keeping my raw files in the native format and not converting to DNG. Converting would limit my raw converter choice to essentially just Adobe, and I happen to like a least a couple of other ones better. I don't loose any sleep over the possibility that I'll not be able to find a converter for my current files in the future. For the worst case I have a copy of the source code for dcraw, but really doubt it'll ever come to that. The idea of a standard raw format in a good one, but I don't think that the major camera makers and the other raw converter vendor would trust Adobe enough to go along. Some do. For example the Pentax K10D has a DNG output option.

Yeah... Could use a manta in the background also.

A friend of mine is considering a trip to Barbados and is trying to find out what the diving is like. I have not heard much about the diving there. Please post if you have any info or recommendations. Thanks.